1. Field of the Invention
The present invention relates to a method and apparatus for controlling congestion in a wireless communication system. More particularly, the present invention relates to a method and apparatus for enabling a base station to control congestion using a caching proxy.
2. Description of the Related Art
Voice call service-oriented Wireless communication systems are evolving to high-speed and high-quality wireless packet data communication systems that provide data and multimedia services. Various standards for wireless communication, such as the recent 3rd Generation Partnership Project (3GPP) based High-Speed Downlink Packet Access (HSDPA), High-Speed Uplink Packet Access (HSUPA), Long Term Evolution (LTE), LTE Advanced (LTE-A), 3GPP2 High Rate Packet Data (HRPD), IEEE 802.16, and the like were developed to support high-speed and high-quality wireless packet data transmission services.
LTE systems were developed to efficiently support high-speed wireless packet data transmission, maximizing wireless system capabilities using various wireless access technologies. LTE-A systems are advanced versions of LTE systems and have improved capabilities of data transmission compared with LTE systems. For convenience of explanation, LTE and LTE-A systems will be herein collectively referred to as LTE systems.
In the LTE system, a general network structure for data exchange with an Internet Protocol (IP) network may be understood as an Evolved Packet System (EPS) defined in 3GPP, and an amount of mobile traffic, such as web-based content exchanged between the IP network and EPS, has rapidly increased as popularity of smartphones spread.
Accordingly, many technologies have been developed and implemented for a base station in the LTE system to increase transmission rate of web content. One of those technologies is implemented by a base station of the LTE system to reduce a transmission time for data, such as web content between the LTE system and the IP network, such as the Internet, by using a caching proxy as a local cache. A base station that uses the caching proxy will now be called a caching evolved Node B (eNB).
Web content or data to be transmitted downlink from the IP network to a User Equipment (UE) via the caching eNB of the LTE system is sent to a Packet Data Convergence Protocol (PDCP) through a proxy layer in a protocol stack of the caching eNB. The proxy layer caches data transmitted downlink from the IP network (e.g., the Internet) and sends the data to the PDCP layer. The proxy layer caches data transmitted uplink from the PDCP layer and transmits the data to the IP network. The data sent through the proxy layer may be used in the IP network, such as HyperText Transfer Protocol (HTTP) based data.
Taking the LTE system as an example, the PDCP layer compresses header information of IP packets exchanged between the EPS and the IP network to increase data transmission efficiency. The PDCP layer serves to forward PDCP Packet Data Units (PDUs) (hereinafter referred to as “PDUs”) to a Radio Link Control (RLC) layer, the PDUs being formed by performing known PDCP processing, such as header compression (for user-plane data), integrity processing (for control-plane data), ciphering, header addition of the PDCP layer, and the like, on IP packets (e.g., PDCP Service Data Units (SDUs) (hereinafter referred to as “SDUs”)) sent from the proxy layer in downlink. The PDCP also decompresses headers of the PDUs sent from the RLC layer in uplink, reconstructs the headers of the PDUs into SDUs, and forwards the SDUs to an upper layer.
In the LTE system, an eNB typically includes PDCP entities that serve as the PDCP layer. When a delay occurs in a PDCP process of configuring a PDU with an SDU received in downlink and forwarding the PDU, the PDCP entity discards the SDU. With respect to such an operation of discarding an SDU, the PDCP entity uses a discard timer that counts delayed time.
The PDCP entity drives the discard timer each time an SDU is received, and discards the SDU if the PDCP processing for the SDU has not been completed for some reason until expiration of the discard timer. However, because the discard timer is driven each time an SDU is received, if the discard timer happens to expire frequently due to bad network conditions, the PDCP entity operates inefficiently and thus causes traffic congestion.
Therefore, a need exists for a method and apparatus for enabling a base station to control congestion using a caching proxy in a wireless communication system.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention.